1. Field of the invention
The present invention relates to a lens sheet and a photoelectric conversion module.
2. Description of the Related Art
In recent years, solar power generation systems have attracted attention as a sustainable energy source and are expected to be more efficient. One method for improving the efficiency of solar power generation systems is to effectively irradiate a photoelectric conversion element with light.
Some photoelectric conversion modules used in solar power generation systems have a structure in which grid electrodes are provided on top of a photoelectric conversion element. In that case, electric current generated by the photoelectric conversion element is taken out through the grid electrodes. The grid electrodes can decrease electric resistance in taking out current, but at the same time decreases the size of light-receiving portions of the photoelectric conversion element by the area of the grid electrodes, which results in a decrease in conversion efficiency.
Therefore, a method of using lenses to effectively utilize light to be incident on the grid electrodes is disclosed in Patent Document 1, for example. A photoelectric conversion module disclosed in Patent Document 1 includes a series of prismatic lenses or cylindrical lenses over a photoelectric conversion element and grid electrodes. Furthermore, boundaries between the lenses are disposed to be above the grid electrodes. Accordingly, light incident on portions above the grid electrodes is refracted so as to be focused to light-receiving portions, whereby incident light can be effectively utilized.
On the other hand, for effective utilization of light in a liquid crystal display, a lens sheet for effectively irradiating liquid crystal with light from a backlight has been developed. For example, a lens sheet having, on both sides, arrays of series of lenses which are shifted from each other by 0 or half the pitch is disclosed in Patent Document 2.